91 Nissan Maxima radiator fans run continuously.

Relays do what relays are told.

I am not familiar with the 91 Maxima either, but there has to be a switch (coolant temperature switch?) somewhere on that vehicle 'telling' the relay (and fan) to do it's thing.

I would start looking around at the lower radiator for a switch (2 or 3 wire) plug. Some switch has to be saying, "the engine is hot or the A/C is on"

Best wishes, Dave

Thanks Dave, there was no fan switch as you mentioned, however, there is only the engine coolant temp sensor. The problem was solved.

It turns out to be an improper bleeding to my knowledge. Here's what I did, if this may help others in the future. I may have left out details in the beginning unintentionally.

First, my grandfather had the water pump replaced by another individual. Then after they refill the coolant the fans ran continuously. Disconnecting the coolant temp sensor did not stop it. Finally, I remove the coolant temp sensor and boil it on a can while I watch for a change in resistance. Nothing change. The resistance stays still. I put it back in and bleed the coolant. I've found many trapped air. I slide the heater dial to maximum and find what looks like tiny bubbles. The fan began to operate normally for the first time after a week.

Here's how I bleed. I remove the cap and idle the car until the water begins to flow in the filler neck. I keep topping it off. I ran the motor for a total of 30-40 minutes. Once I see no air I close the cap.

Lesson learn. Nissan is not a car I want to own. I'd prefer a Honda Civic or a Toyota. These cars are reliable and easy to work on. Actually, no combustion type car is any reliable or make us independent from some sort of industry. I want an electric car where repairs are almost nonexistence.